Cloud modernization for always-on financial services

For financial institutions, cloud modernization should not end at migration. Moving workloads to a new environment is important, but the bigger challenge comes after cutover: how to keep digital services available, responsive and trusted when systems of record are under pressure, offline for maintenance or changing more slowly than customer expectations. In financial services, resilience is not a background concern. It is a defining measure of whether modernization is actually working.

That is why leading institutions are treating cloud as more than infrastructure. They are using it as the foundation for resilient digital operations. When cloud migration is combined with reusable platform patterns, containerized architecture, infrastructure as code and near real-time access to critical data, organizations can create digital services that continue to perform even when legacy estates are constrained. The result is not simply faster delivery. It is continuity by design.

Many financial institutions have already begun moving important customer journeys to the cloud. The value of that move is clear: teams gain a more scalable, secure and responsive platform for delivering digital experiences. But the institutions that create lasting advantage are the ones that use migration to establish repeatable foundations for what comes next.

At Nationwide Building Society, Publicis Sapient helped migrate key digital journeys to a resilient enterprise cloud platform on AWS with zero downtime and a 50% faster migration timeline. That work did more than relocate applications. It created a containerized platform integrated with shared services and security controls, and it established reusable components, onboarding templates, governance models and documentation that future teams could build on. In other words, the migration created a path not only for one successful move, but for faster, safer modernization across the wider estate.

This is what day-two cloud modernization looks like in practice. The goal is not to celebrate a successful migration as an endpoint. It is to use migration to create a consistent, repeatable and secure operating model for future delivery.

Always-on financial services depend on more than hosting. They require a cloud foundation engineered for resilience. Nationwide’s digital platform was built as a cloud-native, containerized, elastic, resilient and secure environment powered by AWS. It was shaped by code-first, automation-first and security-first principles, creating a platform that was easier to scale, govern and reuse.

Infrastructure as code played an important role in making that possible. By standardizing infrastructure through repeatable patterns, teams could improve efficiency, strengthen auditability and reduce the friction involved in migrating or launching journeys. Technologies such as EKS, EC2, RDS, CloudFront, WAF and CloudTrail, alongside tools like Terraform and Helm, helped provide the consistency and control needed in a regulated environment.

The strategic advantage of this approach is that it reduces dependence on one-off engineering effort. New journeys do not need to be assembled from scratch each time. They can inherit proven patterns for deployment, security, scalability and operations. That lowers risk while increasing speed, which is exactly the balance financial institutions need.

Even the best cloud platform cannot deliver always-on service if every customer interaction still depends directly on legacy systems of record. Many financial institutions continue to rely on core platforms that are essential to the business but not designed for today’s always-on digital expectations. As demand rises across mobile, web and assisted channels, direct dependence on those systems can create bottlenecks, limit agility and make maintenance windows more disruptive than they should be.

A more resilient model is to decouple customer-facing channels from legacy back ends. That is where a modern data layer becomes critical. Rather than forcing every digital interaction to read directly from traditional systems, institutions can create a near real-time layer that captures changes as they happen, structures data for consumption and exposes it consistently across channels through microservices and APIs.

This architectural shift creates a buffer between customer experience and core-system volatility. Digital channels can remain responsive during outages, scheduled downtime or spikes in demand, while systems of record continue to evolve at the pace required for control, governance and risk management.

Nationwide’s Speed Layer shows how this works in practice. Developed in collaboration with Publicis Sapient, Speed Layer is a near real-time cache built on a modern technology stack. It collects changes from legacy systems of record using change data capture and streaming technologies, stores important data in a highly scalable layer structured for consumption and makes that data available to applications through microservices and APIs.

The impact was measurable. Speed Layer microservices achieved response times of just 7 milliseconds. Around 300 million records were loaded into MongoDB with real-time streaming before launch, and daily reconciliation across MongoDB and Kafka topics against systems of record took less than 45 minutes. The solution also supported more than 24 million weekly app logins and contributed to around £4 million in infrastructure savings through advanced engineering and performance testing.

More importantly, the architecture created a new digital operating model. Critical information remained available across channels even when backend systems faced disruption or scheduled downtime. By standardizing data access, Nationwide was able to strengthen resilience while making it easier to create new digital products and experiences.

Modernization in financial services rarely means replacing everything at once. The more realistic goal is purposeful coexistence: enabling fast-moving digital capabilities to evolve alongside slower-moving core systems without compromising service continuity. Nationwide’s architecture demonstrates how to do that well.

Its two-speed IT model allows customer-facing capabilities to move at digital speed while core platforms continue to support processing and change on an appropriate timetable. The cloud platform provides the operational foundation. The modern data layer provides the decoupling mechanism. Together, they let product and engineering teams launch new journeys, improve performance and respond faster to customer needs without waiting for every dependency in the legacy estate to be transformed first.

This is more than technical flexibility. It is a way to reduce the blast radius of change. Teams can work in shorter cycles, introduce improvements with more confidence and protect continuity even as modernization progresses.

When institutions build this kind of foundation, resilience becomes an enabler of growth rather than a constraint on change. Nationwide’s modern data layer is positioned not only to keep services online, but to support future use cases such as real-time notifications, personalized banking products, fraud monitoring and broader event-driven experiences. Because data is easier to access, enrich and distribute, innovation becomes faster and less dependent on fragile point-to-point integration.

The same principle applies across cloud modernization more broadly. Reusable cloud patterns, shared services, automation and standardized controls do not just improve delivery efficiency. They create the conditions for continuous modernization, where each new journey benefits from what the organization has already proven.

The lesson for financial services leaders is clear: moving to the cloud is only part of the story. The real opportunity is to modernize in a way that keeps critical services available, data accessible and digital experiences responsive even when legacy systems are under strain.

That requires more than infrastructure migration alone. It requires containerized platforms, infrastructure as code, reusable cloud patterns, strong governance and resilient data access models that decouple channels from core systems. When those elements work together, institutions can create digital operations that are faster to evolve, easier to scale and better prepared for disruption.

For customers and members, the outcome is simple: services that keep working. For the business, it is far more strategic: a digital foundation that turns cloud modernization into operational continuity, better performance and room to innovate with confidence.

Relevant Links

• Speed Layer for Nationwide Building Society
• Speed Layer for Nationwide Building Society
• How modern data foundations turn inclusive lending into a scalable growth engine
• Resiliency Engineering in Financial Services: A Playbook for Modernizing Without Compromising Trust
• Modernize Insurance with Real-Time Data Streaming—Without Replacing Core Systems All at Once
• Moderniser la banque de détail en France : résilience, rapidité et innovation sans rompre avec le cœur du système (Europe)
• Resiliencia digital para la banca en México: cómo modernizar sin poner en riesgo la continuidad (LATAM)
• FAQ (FAQ)
• 12 Things Buyers Should Know About Publicis Sapient’s Work With Nationwide Building Society (LIST)